Weather News

Rain and Mountain Snowmelt Could Lead to Northwest Flooding

March 11, 2013; 8:30 AM

Steady rain will return to parts of the Pacific Northwest early this week along with mild temperatures. These temperatures will lead to snowmelt in the mountains and foothills. The combination of the rain and snowmelt could then cause local flooding problems.

Parts of the Pacific Northwest have been relatively dry over the past two months. In fact, Seattle has only received 55 percent of its average rainfall since February 1st.

A similar story is found in Portland where there has only been 36 percent of normal rainfall since February 1st.

Things will change across parts of the region early this week as a stream of moisture moves onshore into western Washington and southwest British Columbia.

Steady rain will fall Monday afternoon through at least the day on Wednesday, bringing upwards of 1-2 inches of rain to Seattle metro area and 3-5 inches along the coast.

Across the foothills, rising snow levels to above 6,000 feet by late Tuesday combined with an expected 4-6 inches of rainfall through Wednesday will lead to substantial melting of the snow pack.

This increased melting combined with the heavy rain has the potential to cause rapid rises in streams and creeks. Roadside ditches may also become filled with melting snow and slush.

Some larger scale river flooding is even possible, especially beginning late in the day Tuesday and running through midweek but with rainfall amounts still uncertain at the moment, more details will come on this over the next day or two.

This wet weather pattern will continue through the end of the week before drier air moves into the Northwest this weekend.

Residents, especially those living near flood-prone areas, will want to keep an eye on the changing weather situation.